digitalimageprocessing - Rafael C. Gonzalez is a complete package
but if u have a time constraint and want to learn faster u should download imageprocessing codes from net and try to understand various functions believe me its much faster.
u can start with a basic red color tracking code.... (...)

I want to learn imageprocessing so that I can use its algorithms in my future projects. Which one of the following books should I start with?
digitalimageprocessing-Gonzalez
Practical image and Video processing Using MATLAB - O. Marques ,Wiley (...)

Gonzales and Woods is a homily name in digitalimageprocessing.
If you want further details then get DIP by A K Jain.
the properties are mentioned in both of them.
Seperability is nothing much complicated....its just that you split the 2-D transform to 2 1-D transfoems for reducing computaional complexity.